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COATINGSPRO ROOF COATINGS 2017 25
Aliphatic urethane coatings are non-yellowing and very
UV stable. ey can be made in bright colors, too, and meet
most VOC rules. Polyurea coatings are of importance to the
SPF contractor because spray foam equipment can be used to
apply these tough, low VOC materials. ey are best thought
of as a type of urethane, but they cure so fast that they are not
moisture sensitive. Finally, within the acrylic coatings, they
can be made with more resin and at a higher level of solids.
ese products can pass the FM Severe Hail test and are often
used in specifications supporting longer warranties. ey have
physical properties approaching the values for urethanes and
are an important water-borne option.
The Right Coating
In selecting the best product for a specific application,
consider a broad sampling of characteristics, such as the
"Coating Scorecard." It includes performance, weather/
regional suitability, and safety as the broad outline, and then
calls out the specifics under those headings. In terms of the
process, start with adhesion, permeance, and VOC (shown
in bold). ese are the yeses and nos of coating selection. It
must be legal; that means it meets VOC rules and the fire
safety needs. It must bond to the surface, and that bond must
be true when it's very wet to resist ponding water and the
inevitable " bird baths." It must be the right type of coating in
terms of permeability so it won't trap or accumulate water.
e rest of the properties are on a sliding scale, from just
adequate to best, and they should be seen as in a balance. at
balance will not be the same in all regions, clients, or types
of roofing. Finally, a key determining factor might include
a project-specific need, such as freeze-thaw resistance, heat
stability, hail, foot traffic resistance, or crack bridging.
ere are a variety of different coatings out there, and it's
important to figure out which coating is the right one for each
project. CP
Steven Heinje is t he technica l manager for GA F 's Liqu id Appl ied Systems,
headquar tered in Parsippany, NJ. He has 32 years of research and develop-
ment (R&D) e x per ience in coat ings. He is cha ir man of t he Roof Coat ing
Manufact urers A ssociat ion (RCM A) Codes Task Force. Heinje cont r ibutes
e x tensively to A STM D08–Roof ing and has w r itten many ar t ic les. For more
infor mat ion, contact: GA F, w w w.gaf.com
So Many Coatings
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